Conventionally, a motor drive apparatus is known which converts DC power supplied from a battery into three-phase AC power with an inverter, supplies the three-phase AC power to a motor, and thereby, drives the motor.
In such a motor drive apparatus, a smoothing capacitor for smoothing a DC voltage is provided on an input side of the inverter. Generally, at the time of stopping operation of the motor, the connection between the battery and the capacitor is shut in order to suppress power consumption of the battery. Nevertheless, since the capacitor is in the state where charge is accumulated in this stage, it is needed to discharge the charge quickly.
As one way of discharging the charge in the capacitor, for example, it can be considered that a discharge resistor is connected to both ends of the capacitor. However, it is not preferable that the discharge resistor is disposed, which causes the apparatus to be large.
A method of the discharge by causing the charge in the capacitor to flow in the motor is also proposed. For example, PTL 1 discloses a method in which a magnetic pole position of a rotor is detected, a torque current component Iq is configured to be zero, a magnetization current component Id is set to be a predetermined value, and thereby, the energy accumulated in the capacitor is caused to be consumed with windings of the motor without rotating the motor.